# Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting') (CWE-113)

The product receives data from an HTTP agent/component, and it places this data in HTTP response headers without neutralizing CRLF sequences.

- Prevalence: मध्यम 3 भाषाएँ कवर की गईं
- Impact: उच्च 2 उच्च गंभीरता वाले नियम
- Prevention: प्रलेखित 3 फिक्स उदाहरण

**OWASP:** Injection (A03:2021-Injection) - #3

## Description

An attacker can inject CRLF sequences into HTTP headers to create additional headers or response body content. This can lead to cache poisoning, cross-site scripting, or other attacks.

## Prevention

3 Shoulder डिटेक्शन नियमों पर आधारित HTTP Response Splitting के लिए रोकथाम रणनीतियाँ।

### Go

Strip CRLF characters from user input before setting HTTP headers

### Python

Strip CRLF characters from user input before using in HTTP headers

## Warning Signs

- [HIGH] user input flowing into HTTP response headers without CRLF sanitization
- [MEDIUM] user input flowing to HTTP headers without CRLF sanitization

## Consequences

- अनधिकृत कोड निष्पादित करना
- सुरक्षा तंत्र को बायपास करना
- एप्लिकेशन डेटा संशोधित करना

## Mitigations

- HTTP प्रतिक्रिया हेडर में उपयोगकर्ता इनपुट को कभी सीधे शामिल न करें
- हेडर में शामिल किए जा सकने वाले सभी उपयोगकर्ता इनपुट को सैनिटाइज़ करें
- हेडर सेट करने के लिए फ़्रेमवर्क-प्रदत्त उन विधियों का उपयोग करें जो एनकोडिंग संभालती हैं

## Detection

- Total rules: 3
- Languages: go, javascript, typescript, python

## Rules by Language

### Go (1 rules)

- **HTTP Header Injection** [MEDIUM]: Detects user input flowing to HTTP headers without CRLF sanitization.
  - Remediation: Remove CRLF characters from user input before setting headers.

```go
value := strings.ReplaceAll(userInput, "\r", "")
value = strings.ReplaceAll(value, "\n", "")
w.Header().Set("X-Custom", value)
```

Learn more: https://shoulder.dev/learn/go/cwe-113/header-injection

### Javascript (1 rules)

- **HTTP Header Injection (Response Splitting)** [HIGH]: Detects user input flowing into HTTP response headers without CRLF sanitization.
  - Remediation: Remove CRLF characters from user input before setting headers.

```javascript
const sanitized = userInput.replace(/[\r\n]/g, '');
res.setHeader('X-Custom-Header', sanitized);
```

Learn more: https://shoulder.dev/learn/javascript/cwe-113/header-injection

### Typescript (1 rules)

- **HTTP Header Injection (Response Splitting)** [HIGH]: Detects user input flowing into HTTP response headers without CRLF sanitization.
  - Remediation: Remove CRLF characters from user input before setting headers.

```javascript
const sanitized = userInput.replace(/[\r\n]/g, '');
res.setHeader('X-Custom-Header', sanitized);
```

Learn more: https://shoulder.dev/learn/javascript/cwe-113/header-injection

### Python (1 rules)

- **HTTP Header Injection** [HIGH]: Detects user input flowing into HTTP response headers without CRLF
sanitization.
  - Remediation: Remove CRLF characters from header values.

```python
import re
safe_value = re.sub(r'[\r\n]', '', user_value)
```

Learn more: https://shoulder.dev/learn/python/cwe-113/header-injection